[clang] [Clang][Modules] Emit C++20 BMIs to working directory with -fmodule-output (PR #174560)

[via cfe-commits]

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@@ -51,7 +51,7 @@
 
 // RUN: %clang -std=c++20 Hello.cppm --precompile -fmodules-reduced-bmi \
 // RUN:     -### 2>&1 | FileCheck Hello.cppm \
-// RUN:     --check-prefix=CHECK-OVERRIDE-WARN
+// RUN:     --check-prefix=CHECK-OVERRIDE-WARN-NOT
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CarvedCoder wrote:

i wrote a test for the generated .pcm file 
`
//RUN: mkdir %t/build
// RUN: cd %t/build
// RUN: %clang -std=c++20 %t/Hello.cppm -fmodule-output -c -### 2>&1 | FileCheck %t/Hello.cppm --check-prefix=CHECK-CWD
// CHECK-CWD: -fmodule-output={{.*}}/build/Hello.pcm
`
but it seems to be causing problems in Driver/module-fgen-reduced-bmi.cppm 

https://github.com/llvm/llvm-project/pull/174560